Calculations with the STCP version of MARCH were performed as part of the Three Mile Island Unit 2 (TMI-2) Analysis Exercise. In the light of the present knowledge of what happened at TMI-2, a number of modeling enhancements were found necessary to interpret the accident. These enhancements and the results of calculations are described. The modified version of MARCH reproduced many of the key accident signatures, including the timing of core heatup, reasonable predictions of the core melt and cladding reaction fractions, the primary system pressure, and the hydrogen release to the containment, which eventually produced a burn at 10 h.